On-board diagnostics is a system in a vehicle for monitoring issues related to emissions and possibly other vehicle issues. Various sensors are connected to the on-board diagnostics to monitor components having an effect on emissions. If one of the sensors detects an issue, then the on-board diagnostics illuminates a “check engine” light. The on-board diagnostics includes a connector to which a technician can plug in a tool to read a diagnostic trouble code (DTC). The diagnostic trouble code corresponds to the issue detected by one or more of the sensors. Vehicles manufactured after 1996 and sold in the United States are required to have on-board diagnostics conforming to the OBD-II standard.